741 Operational amplifier

741 Operational amplifier Tutorial

INTRODUCTION

An operational amplifier, often referred to as an Op Amp, is a very high gain performance amplifier designed to amplify ac and dc signal voltages. Modern integrated circuit technology and large scale production techniques have brought down the prices of such amplifiers within reach of all amateurs, experimenters and hobbyists. The Op Amp is now used as a basic gain element, like an elegant transistor, in electronic circuits.

Fig.1. Symbol For An Operational Amplifier

A symbol used to represent an operational amplifier in schematics is shown in Fig.1. The operational amplifier has two input and only one output. One input is called the inverting input and is denoted by a minus sign. A signal applied to this input appears as an amplified but phase inverted signal at the output. The second input is called a non-inverting input and is denoted by a plus sign. A signal applied to this input appears at the output as an amplified signal which has the same phase as that of the input signal.

The availability of two input terminals simplifies feedback circuitry and makes the operational amplifier a highly versatile device. If a feedback is applied from the output to the inverting input terminal, the result is a negative feedback which gives a stable amplifier with precisely controlled gain characteristics. On the other hand, if the feedback is applied to the non-inverting input, the result is positive feedback which gives oscillators and multivibrators. Special effects are obtained by combination of both types of feedbacks.

Fig.2. Pin Configurations for 741 Op amp

Of the different types of operational amplifiers produced, type 741 has achieved a very wide popularity. It is available in 14-pin dual-in-line, 8-pin-dual-in-line or TO-style packages. Pin configurations for all these packages are shown in Fig.2.

Fig.3. Pin Configurations for Type 747 Dual Op Amp

Integrated circuit type 747 accommodates two type operational amplifiers in a single package. Pin configurations for different packages are shown in Fig.3.